Implement generalized function types.

pkg/testing/lib/src/analyze.dart

Index: pkg/testing/lib/src/analyze.dart
diff --git a/pkg/testing/lib/src/analyze.dart b/pkg/testing/lib/src/analyze.dart
index 38324578eb580224d94f9e0b942070cef0c29921..ae689c8cf2ee4b167063f85169b7ca67473d4a6e 100644
--- a/pkg/testing/lib/src/analyze.dart
+++ b/pkg/testing/lib/src/analyze.dart
@@ -166,8 +166,10 @@ Future<Null> analyzeUris(Uri analysisOptions, Uri packages, List<Uri> uris,
   bool hasOutput = false;
   Set<String> seen = new Set<String>();
   for (AnalyzerDiagnostic diagnostic in diagnostics) {
-    String path = diagnostic.uri?.path ?? "<unknown>";
-    if (exclude.any((RegExp r) => path.contains(r))) continue;
+    String path = diagnostic.uri?.path;
+    if (path != null && exclude.any((RegExp r) => path.contains(r))) {
+      continue;
+    }
     String message = "$diagnostic";
     if (seen.add(message)) {
       hasOutput = true;